FILE - In this Tuesday, Sept. 11, 2012 file photo, members of the Mujahedeen-e-Khalq organization are seen inside the Liberty refugee camp in Baghdad, Iraq. Iraqi police say assailants have fired rockets at a refugee camp for an Iranian exile group outside Baghdad, killing at least six people and wounding more than 40. The camp houses members of the Mujahedeen-e-Khalq, the militant wing of the Paris-based National Council of Resistance of Iran. (AP Photo/ Hadi Mizban, File)

Rockets and mortar rounds struck a refugee camp for Iranian exiles next to Baghdad's international airport before dawn Saturday, killing six people and wounding about 40, police and U.N. officials said.

U.N. Secretary-General Ban Ki-moon condemned the attack. He urged Iraqi officials to bring the attackers to justice, noting that the government is responsible for the safety of the camp residents.

The government said it opened an investigation, but there was little it can do to shield the camp, which is home to about 3,100 people, from rocket attacks. It asked the international community to speed up the resettlement of the refugees.

The camp houses members of Mujahedeen-e-Khalq, or MEK, the militant wing of a Paris-based Iranian opposition group, the National Council of Resistance of Iran. Iraq's Shiite-led, pro-Iranian government considers MEK a terrorist group and is eager to have it out of the country.

"We call on the international community to expedite the procedures ... to find countries for them as quickly as possible," government spokesman Ali al-Moussawi said Saturday.

The refugee camp, located in a former American military base known as Camp Liberty, is meant to be a temporary way station while the United Nations works to find host countries for the refugees.

Camp spokesman Shahriar Kia said 35 rockets and mortar rounds struck the camp. He said more than 100 people were hurt, while the United Nations and police put the number of wounded at about 40.

Before being moved to the Baghdad location, members of the MEK lived in another camp, called Ashraf, in northeastern Iraq. Camp Ashraf was twice raided by Iraqi security forces trying to impose control, leaving more than three dozen people dead.

The MEK, also called the People's Mujahedeen of Iran, opposes Iran's clerical rulers and has carried out assassinations and bombings in Iran. It fought in the 1980s alongside Saddam Hussein's forces in the Iran-Iraq war, and several thousand of its members were given sanctuary in Iraq by Hussein.

The group renounced violence in 2001 and the Obama administration took the MEK off the U.S. terrorism list in late September.